user_name - (Requirement) The name used for log in to your SFTP server.

home_directory - (Optional) The landing directory (folder) for a user when they log in to the server using their SFTP client.

policy - (Optional) An IAM JSON policy document that scopes down user access to portions of their Amazon S3 bucket. IAM variables you can use inside this policy include ${Transfer:UserName}, ${Transfer:HomeDirectory}, and ${Transfer:HomeBucket}. Since the IAM variable syntax matches Terraform's interpolation syntax, they must be escaped inside Terraform configuration strings ($${Transfer:UserName}).

role - (Requirement) Amazon Resource Name (ARN) of an IAM role that allows the service to controls your user’s access to your Amazon S3 bucket.